Polyphenylene ether resin compositions are a well-known class of thermoplastics finding a wide range of which are useful for many plastics applications, including molding and extrusion processes.
Polyphenylene ether resins are often combined with styrenic resins, notably high impact polystyrene, to provide a family of products with varying properties. One of the particularly advantageous properties of the polyphenylene ether resins and alloys are their relatively high heat distortion temperatures. Typically, however, the heat distortion temperature of a thermoplastic is inversely related to the degree of flow such thermoplastics exhibit in a molding process. For example, a plastic having a high heat distortion temperature will not typically flow as easily as the same plastic system having a lower heat distortion temperature. As a result, it is often necessary to plasticize the thermoplastic resin in order to achieve the flow characteristics required for a given application.
Prior art plasticizers for polyphenylene ether resin systems include triaryl phosphates such as triphenyl phosphate or tri-isopropylphenyl phosphate. Such plasticizers are generally successful but are not necessarily suitable for all polyphenylene ether resin applications. Such triaryl phosphates are known to decrease the environmental stress crack resistance of the thermoplastic matrix, and in certain applications this is a disadvantageous result.
It was therefore an object of the present invention to find a non-phosphorous based plasticizing agent which showed the requisite plasticizing effect such as improved flow and lower heat distortion temperature while at the same time avoiding some of the deleterious properties of triaryl phosphate plasticizers.